Interleukin 1 (IL-1) is a protein produced by activated mononuclear phagocytes and performs a broad range of functions in host defense and immunoregulation (Dinarello, C. A. [1984] New England J. Med. 311, 1413-1418). Recently it has been demonstrated that Il-1 is first synthesized as a precursor molecule of about 270 amino acids in length (approximately 30,000 molecular weight) which is proteolytically processed into a smaller molecule (approximately 18,000 molecular weight) which possesses full biological activity (Auron, P. E., Webb, A. C., Rosenwasser, L. J., Mucci, S. F., Rich, A., Wolff, S. M., and Dinarello, C. A. [1984] Proc. Natl. Acad. Sci. U.S.A. 81. The sequence for human IL-1 is shown in Chart A.